Island Packet 35 (1989) — Complete Fresh Water Aluminum Tank Removal & Replaceme

Hello,I own a 1989 Island Packet 35, and I have encountered a serious problem with the original aluminum fresh water tank.After cleaning and inspecting the tank, it became clear that its condition no longer allows me to consider normal flushing or cleaning as a permanent solution. A serious leak has now been found in the tank, so I want to completely remove the old aluminum tank and replace it with a new one.I do not want to repair the old tank in place. My goal is to remove it completely from the boat, gain access to the area underneath it, inspect and restore that area if necessary, and then install a new tank or several new tanks. I have not yet decided on the material for the replacement tank — I am considering aluminum, polyethylene, or fiberglass. At this point, my main concern is the safe removal of the original tank and the proper structural restoration afterward.As I understand from the original IP35 owner’s manual, the interior is constructed around a molded fiberglass structural pan, which forms the cabin sole, bunk and settee surfaces, and incorporates a grid system of plywood and fiberglass reinforcing webs. The structural pan and reinforcing grid are bonded directly to the hull.Therefore, I understand that simply taking a saw and cutting out the entire floor above the tank would not be a good idea without knowing which areas are structural and where the reinforcing members are located.I would really appreciate hearing from IP35 owners who have actually completely removed the original fresh water tank, or who have performed similar work involving the structural pan.In particular, I would like to know:

1. How is the original aluminum fresh water tank actually removed from an IP35? How large an area of the cabin sole/structural pan needs to be opened?
2. Where is it safe to make the cuts? Is there any known layout or drawing showing the reinforcing webs/grid around and above the tank?
3. Is it necessary to remove only the horizontal surface above the tank, or must additional portions of the pan, furniture, or other structures be removed to physically get the tank out?
4. How is the tank itself installed and secured? Once the top is exposed, what actually holds the tank in place? Are there fiberglass structures, fasteners, or other components that must be removed?
5. Can the original tank be removed in one piece, or does it normally have to be cut into sections inside the boat?
6. How should the structural pan be restored afterward? In particular, if any reinforcing webs have to be cut, how were they reconstructed to restore the original strength and stiffness of the structure?
7. Has anyone used this opportunity to create removable access panels or a removable section of the cabin sole, so the replacement tank can be inspected, serviced, or replaced in the future without cutting the interior apart again?
8. What did you use for the replacement: another aluminum tank, polyethylene, fiberglass, or multiple smaller tanks? Were there any issues with installation, securing the tank, venting, or loss of capacity?

I am especially interested in photos of the removal process, photos of the boat with the sole and tank removed, dimensions and locations of the cuts, and any information showing what is directly underneath and around the original fresh water tank.I have found discussions about tank replacement on the IP350 and other Island Packet models where owners did cut portions of the floor to remove the tanks. However, the IP35 construction is different, so before I start cutting into the structural pan I would like to understand as precisely as possible how this has been done specifically on an IP35 and which structural areas must not be compromised.I would greatly appreciate hearing from anyone who has done this job, assisted with it, or seen it done on an IP35. Even old photos, drawings, measurements, or a description of the removal sequence would be extremely helpful.Thank you!